Products normally used in the production of plant growth media for greenhouse crop production are often water repellent (hydrophobic). These products, which are generally soil-free, include various organic materials such as peat moss, sphagnum peat, sedge peat, bark, and the like and have proven to be the most difficult conditions in which plant life may be grown. Such hydrophobic conditions basically prevent, or drastically reduce, the ability of water to infiltrate from the ground level to subterranean root systems. Thus, reduction in water repellency would be helpful in permitting and/or promoting the growth of sustained plant life in such organic plant growth media.
Attempts in this area by others have included the application of wetting agents to plant growth media. Wetting agents are generally substances which are added to surface coatings, water, or oils to increase spreading and penetration action. Wetting agents belong to a group of a more general class of materials called “surface active agents,” hence the term “surfactants.” Characteristic of their properties is the ability to lower surface and interfacial tension between the plant growth media and applied water. Without being bound by theory, it is believed that wetting in soil-free mixtures may occur when the wetting agent is absorbed into, and/or causes inflation of, the natural bladders, or openings, that exist in these organic materials. Wetting may also occur by filling the dead cells within the plant growth media with water.
However, significant problems have been encountered when using some prior art wetting agents. For instance, some wetting agents require “activation” before they become effective, especially if applied in granular form. The granular form tends to become securely adhered to a solid carrier substrate and thus requires repeated cycles of wetting and re-wetting in order to cause the wetting agent to leach from the surface the carrier. Because of this need for activation, it is often the case that increased amounts of wetting agent are needed to provide adequate moisture penetration, which may be expensive and detrimental to the plants. Also, the need for repeated cycles of wetting and re-wetting result in increased water usage which is environmentally wasteful and may be expensive.
Other problems are encountered in the utilization of wetting agent for plant growth media. For instance, many wetting agents lose their ability to effectively wet plant growth media, due to the fact that the plant growth media is dried out for packaging and shipping. The plant growth media may further lose moisture content during storage. As a result of these conditions, the structural openings, or bladders, within the plant growth media tend to close up tightly and keep water from penetrating into the media. Thus, the wetting agents, which often fill these bladders, are not able to come into contact with the water which makes wetting of the plant growth media even more difficult. Furthermore, once activated or in use, the ability of a wetting agent to continuously provide moisture management to the plant growth media tends to decrease over time. As a result of these conditions and properties, the wetting agent has a limited, and often shortened, useful lifespan.
In addition to providing moisture transport within the plant growth media, it is also desirable that the wetting agent possesses other functional attributes. For example, it is desirable that the wetting agent exhibits a sufficient level of durability to repeated cycles of wetting and drying. These conditions are representative of those that the plant growth media may encounter due to rainfall exposure or from repeated cycles of watering in a greenhouse. Additionally, the wetting agent should not interfere with seedling growth, and it is desirable that the wetting agent is environmentally friendly. Also, it is beneficial that the wetting agent is compatible with other horticultural treatments that may be applied to crops, such as herbicides and pesticides.
Thus, it has been found that there exists a need to provide a simple method for achieving effective and long-lasting moisture penetration through such highly hydrophobic plant growth media, in order to obtain water availability at the soil surface, and within the subterranean root systems thereof, without causing detrimental effects to the surface plant life.